U.S. patent number 7,691,106 [Application Number 11/234,754] was granted by the patent office on 2010-04-06 for transverse acting surgical saw blade.
This patent grant is currently assigned to Synvasive Technology, Inc.. Invention is credited to Michael G. Fisher, Jon C. Schenberger.
United States Patent |
7,691,106 |
Schenberger , et
al. |
April 6, 2010 |
Transverse acting surgical saw blade
Abstract
Various embodiments provide surgical cutting devices and systems
for orthopedic and other procedures. Specific embodiments provide
saw devices for accessing and cutting subjacent bone and other
tissue while minimizing injury to surrounding tissue. One
embodiment provides a transverse acting saw blade for performing
surgical cuts to bone tissue with minimal injury to surrounding
tissue. The blade comprises an elongated member having a first
portion and a second portion and a longitudinal and lateral axis.
The first portion is configured to engage a drive source to produce
longitudinal movement of the first portion that is atraumatic to
surrounding tissue. The second portion includes a cutting surface.
The longitudinal movement of the first portion is converted to a
lateral movement of the second portion that is sufficient to cut
engaged bone tissue with the cutting surface. The movement of the
second portion is substantially transverse to the movement of the
first portion.
Inventors: |
Schenberger; Jon C.
(Placerville, CA), Fisher; Michael G. (Folsom, CA) |
Assignee: |
Synvasive Technology, Inc. (El
Dorado Hills, CA)
|
Family
ID: |
37906661 |
Appl.
No.: |
11/234,754 |
Filed: |
September 23, 2005 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20070083209 A1 |
Apr 12, 2007 |
|
Current U.S.
Class: |
606/82 |
Current CPC
Class: |
A61B
17/142 (20161101); A61B 2017/00734 (20130101); A61B
17/14 (20130101) |
Current International
Class: |
A61B
17/14 (20060101) |
Field of
Search: |
;606/79,82,176,177
;30/182,209,214,392 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
International Preliminary Report on Patentability of PCT
Application No. PCT/US2006/037014, issued Mar. 26, 2008, 8 pages
total. cited by other .
Stryker.RTM. Precision Oscillating Tip Saw--Ref 6209, Instruction
for Use, Sep. 2006, 21 pages total. cited by other .
Stryker Precision.TM. Oscillating Tip Saw [pamphlet], 2006, 2 pages
total. cited by other.
|
Primary Examiner: Robert; Eduardo C
Assistant Examiner: Fisher; Elana B
Attorney, Agent or Firm: Townsend and Townsend and Crew
LLP
Claims
What is claimed is:
1. A saw blade for performing surgical cuts to bone tissue with
minimal injury to surrounding tissue, the blade comprising: a
single piece elongated member having a first portion and a second
portion having a cutting surface, wherein the first portion is
engageable with a drive source to produce a longitudinal movement
of the first portion, and wherein the single piece elongated member
has an opening in the second portion behind the cutting surface and
a slot in communication with the opening and extending from the
opening to the first portion so that the first portion is split
into halves which can be separately reciprocated to convert the
longitudinal movement of the first portion into a lateral movement
of the second portion that is sufficient to cut engaged bone tissue
with the cutting surface, the movement of the first portion being
substantially atraumatic to surrounding tissue and the movement of
the second portion being substantially transverse to the movement
of the first portion.
2. The saw blade of claim 1, wherein a portion of the blade is
configured to sense a property of the blade.
3. The saw blade of claim 2, wherein the sensed property is an
applied force, a vibration amplitude or a vibration frequency.
4. The saw blade of claim 1, further comprising: a sensor coupled
to a portion of the blade.
5. The saw blade of claim 4, wherein the sensor includes at least
one of an accelerometer, a pressure sensor, a force sensor, a MEMs
sensor, a piezo-electric sensor or a microphone.
6. The saw blade of claim 1, further comprising a sleeve disposed
over at least a portion of the elongated member, the sleeve
configured to laterally support the blade during cutting and to be
inserted into a cutting guide.
7. The saw blade of claim 1, wherein the opening increases the
lateral flexibility to the second portion relative to the first
portion.
8. The saw blade of claim 1, wherein the opening is configured to
produce a substantially constant stress along a length of the
elongated member adjacent the opening when the drive source engages
the blade.
9. The saw blade of claim 1, wherein the opening is distally
tapered.
10. The saw blade of claim 1, wherein the second opening is
substantially oval, circular or rounded.
11. The saw blade of claim 1, wherein the second portion includes a
plurality of openings.
12. The saw blade of claim 11, wherein the plurality of openings
are arranged in a pattern for converting a longitudinal
displacement of the first portion to a lateral displacement of the
second portion.
13. The saw blade of claim 1, wherein a proximal end of the first
portion is configured to engage the drive source which reciprocates
the two halves.
14. The saw blade of claim 1, wherein the second portion has a
lateral stiffness configured to facilitate conversion of
longitudinal displacement of the first portion to lateral
displacement of the second portion.
15. The saw blade of claim 14, wherein the second portion lateral
stiffness is produced by annealing or tempering the second
portion.
16. The saw blade of claim 14, wherein the second portion includes
an annealed or tempered region.
17. The saw blade of claim 1, wherein at least a portion of the
blade comprises at least one of metal, stainless steel, composite,
carbon fiber composite, polymer, titanium, or ceramic.
18. The saw blade of claim 1, wherein the cutting surface includes
a plurality of teeth.
19. The saw blade of claim 1, wherein the cutting surface is
configured to cut at least one of femoral, tibial, humoral, spinal,
cranial or mandibular tissue.
20. The saw blade of claim 1, wherein at least a portion of the
blade is configured to be used with a cutting guide.
21. The saw blade of claim 1, wherein the first portion has
sufficient length to allow access to bone tissue by the cutting
surface up to about six inches from a skin surface.
22. The saw blade of claim 1, wherein movement of the first portion
exerts a force below that necessary to sever tissue surrounding the
first portion.
23. The saw blade of claim 1, wherein movement of the first portion
exerts a force below that necessary to damage a vasculature or
microvasculature in tissue surrounding the first portion.
24. A surgical saw system for performing surgical cuts to bone
tissue with minimal injury to surrounding tissue, the system
comprising: the saw blade of claim 1; and a surgical saw having a
driver to separately axially reciprocate the two halves of the
blade.
25. The surgical saw system of claim 24, further comprising: a
cutting guide configured to guide the saw blade in cutting bone
tissue.
26. The surgical saw system of claim 24, further comprising a
sleeve disposed over a least a portion of the elongated member, the
sleeve configured to laterally support the blade during cutting.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
Embodiments of the invention relate to surgical saws. More
specifically, embodiments of the invention relate to surgical saw
blades having a mechanical motion configured to minimize trauma to
surrounding tissue not engaged by the blade.
Surgical saws of the sagittal type for performing bone surgery have
been extensively utilized for many years. These saws have normally
employed an elongated saw blade having a toothed segment on one end
thereof, with the other end of the blade being pivotally mounted to
permit angular oscillation of the blade. Typical surgical saws do
not permit deep-reach cutting, without contacting and possibly
damaging adjacent tissue since deep cuts require that the toothed
edge of the blade be spaced a greater distance from the pivot axis,
thereby resulting in larger peripheral movement which often causes
damage to the tissue surrounding the bone. In particular they do
not provide an atraumatic means of transmitting motion to the
cutting portion of the blade. Additionally, smaller surgical
incisions as popularized by less-invasive surgical techniques
reduce the width-to-length ratio, increasing the possibility of
damaging adjacent tissue.
While some devices have attempted to use various mechanisms gears,
belts, pulleys or linkage rods etc. to transmit motion to a cutting
portion of the blade without having one long moveable blade
connected to a drive source, these devices have the drawback of
having complicated mechanisms which can be difficult and costly to
assemble.
Accordingly, there is a need for a surgical saw and saw blade which
can be threaded through surgical access incisions, fed down to
tissue or bone requiring cutting or resection, and make the cut or
perform the resection without injuring or endangering the
surrounding bone or tissue. There is also a need for a surgical saw
and saw blade which can be utilized for deep cuts while maintaining
minimal, atraumatic motion of the longitudinal sides of the saw
blade, and transverse motion of the toothed end of saw blade,
allowing effective cutting and or resection of tissue or bone.
BRIEF SUMMARY OF THE INVENTION
Various embodiments provide surgical cutting devices and apparatus
for orthopedic and other surgical procedures. Specific embodiments
provide saw devices for accessing and cutting subjacent bone and
other tissue while minimizing injury to surrounding tissue. One
embodiment provides a transverse acting saw blade for performing
surgical cuts to bone tissue with minimal injury to surrounding
tissue. The blade comprises an elongated member having a first
portion and a second portion and a longitudinal and lateral axis.
The first portion is engageable with a drive source to produce
longitudinal movement of the first portion that is atraumatic to
surrounding tissue. The second portion includes a cutting surface.
The longitudinal movement of the first portion is converted to a
lateral movement of the second portion that is sufficient to cut
engaged bone tissue with the cutting surface. The movement of the
second portion is substantially transverse to the movement of the
first portion. As will be described herein, the motion of the
cutting portion is achieved through the structural design of the
blade body itself vs. the use of gears, belts, chains, linkage
rods, etc. This allows for low cost and ease of manufacturability
of the blade.
The elongated member can include a motion converter configured to
convert longitudinal displacement of the first portion to a lateral
displacement of the second portion. In preferred embodiments the
motion converter comprises an opening disposed on the elongate
member which can include a first opening and second opening. The
first opening has a shape configured to bias the first portion
toward longitudinal movement when engaged by the drive source and
the second opening has a shape configured to convert a longitudinal
displacement of the first portion to a lateral displacement of the
second portion. In a preferred embodiment the first opening is slot
shaped and the second opening has at least a partially rounded
shape and can comprise a plurality of openings. Also at least one
of the first and second portions or the motion converter can have
differing chemical composition, mechanical properties, and
geometrical shapes, including three-dimensional shapes, such as
surface contours designed to enhance the motion conversion. These
differing properties can be produced by annealing or tempering
selected portions of the blade using laser, induction heat, or
other methods. Three dimensional shapes including surface contours
can be chemically-milled, cast, forged, cold-formed, laser-milled,
electronic-discharged machined, conventionally machined or molded
into the motion converter.
The drive source can be positioned on the saw device and can be a
mechanical, electrical, hydraulic or pneumatic drive. In a
preferred embodiment, the drive source is a rotary drive source
including a cam which engages the blade to effect reciprocal motion
of the first portion of the elongated member. In many embodiments,
the blade can include a sleeve disposed over at least a portion of
the elongated member. The sleeve is configured to laterally support
the blade during cutting, while the sleeve itself remains
stationary. The sleeve can also be configured to fit tightly in or
on various cutting guides without causing high-speed friction on or
in the cutting guide. The sleeve can have lumen configured to
provide irrigation of the blade or target tissue site. The sleeve
can comprise polymer or other material and can also include a
lubricous coating on an inner lumen wall.
Another embodiment provides a surgical saw system for performing
surgical cuts to bone tissue with minimal injury to surrounding
tissue. The system comprises an embodiment of the saw blade
described above and a surgical saw configured to use the blade. The
saw device is typically a reciprocating saw and can be hand held.
The device can include one or more conduits or connections to
provide power to the drive source as well as connections for
irrigation/aspiration and connections for electrical coupling to
the blade or to sensors positioned on the blade. The system can
also comprise a cutting guide configured to be used with the blade
and the saw device.
An exemplary method of using an embodiment of the transverse acting
blade the surgeon can make a small usually linear incision above
the target tissue bone, for example the femur. The distal portion
of the saw blade is then inserted through the incision either
directly or through a port or cutting guide. Then by visual
guidance, by feel, or image guidance (e.g., infrared, radio,
electromagnetic, ultrasonic, arthroscopic or other viewing means)
the distal portion of the blade is advanced until the target tissue
bone is reached. Surrounding tissue, such as bone or fascia, can be
pushed aside or partially retracted. The drive source is then
activated and cutting begins. The cutting can also be done under
image guidance, by direct viewing of the surgical site, by feel or
a combination thereof. The surgeon can make a continuous cut
without the need to stop due to the risk of injuring adjacent
tissue. Longer cuts can be made by angling the proximal portion of
the blade side to side through the incision site such that distal
end moves through a desired cutting length. During this process,
the lateral motion of the non-cutting section of the blade remains
negligible such that non cutting portion is tissue atruamatic.
Depending upon the blade, the applied force and blade speed can be
monitored to stay within desired ranges. Also irrigation and
aspiration can be used at the surgeon's discretion. Depending upon
the embodiment, irrigating fluid can be supplied through a channel
in the blade or externally. Upon completion of the cut, the blade
is removed. These and other embodiments and aspects of the
invention are described in further detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a lateral view of an embodiment of a surgical cutting
system having a transverse acting blade.
FIG. 1a is a lateral view of an embodiment of a transverse acting
blade
FIG. 1b is a perspective view of the distal portion of the
embodiment of FIG. 1a.
FIG. 2a is lateral view of another embodiment of a transverse
acting blade.
FIG. 2b is a perspective view of the distal portion of the
embodiment of FIG. 2a.
FIG. 3a is a lateral view of another embodiment of the saw
blade.
FIG. 3b is a lateral view illustrating transverse action of the
blade of embodiment 3a.
FIG. 4a is a lateral view illustrating engagement of the blade with
tissue.
FIG. 4b is a lateral view illustrating use of the blade to make a
long lateral cut in tissue
FIG. 5a is a perspective cut away view illustrating engagement of a
rotary drive source with a transverse acting blade.
FIGS. 5b-5d are lateral views illustrating transverse movement of
the blade using the rotary drive source.
FIGS. 6a and 6b are lateral views illustrating use of another
embodiment of a drive source to produce transverse movement of the
blade.
FIG. 7a is lateral view of an embodiment of the transverse acting
blade having a sleeve.
FIG. 7b is lateral view illustrating movement of a transverse
acting blade within the sleeve.
FIG. 8 is lateral view of an embodiment of the transverse acting
blade having force limiting capability.
FIG. 9 is a lateral view of an embodiment of a transducing saw
blade.
FIG. 10 is a lateral view illustrating use of a transverse acting
blade with a cutting guide.
FIG. 11 is a lateral view illustrating an embodiment of the blade
having a stop to limit lateral movement.
FIG. 12 is a lateral view illustrating an embodiment of the blade
having a convoluted portion.
FIG. 13 is a lateral view illustrating another embodiment of the
blade having a convoluted portion engaged by a drive source.
FIG. 14 is a lateral view illustrating an embodiment of the blade
configured to have increased lateral movement of the cutting
section.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIGS. 1-5, in various embodiments a saw blade
system 5 can include a saw blade 10 configured to be engaged by a
drive source 20 to cut a target tissue site 30 (or cutting site) of
bone 30b or other tissue 40. In many embodiments, blade 10
comprises an elongated member 50 having a lateral axis 51 and
longitudinal axis 52. Elongated member 50 includes a proximal
portion 60 and distal portion 70. Proximal portion 60 includes a
proximal end 61 and an engagement section 62 configured to movably
engage drive source 20. Distal portion 70 includes a distal end 71
a cutting section 72 which can comprise a plurality of teeth 74
which make a cut or kerf 31 at the tissue site. Drive source 20 can
be incorporated into a saw device 25 described herein.
In many embodiments, the blade can include one or more openings or
spaces 53 which can positioned on one or both of proximal and
distal portions 60 and 70. Opening 53 is sized and shaped to
convert or translate movement of the proximal portion in one
direction (typically longitudinal) into movement of the cutting
section 72 in another direction (typically lateral). Also opening
53 serves to convert reciprocal movement of proximal portion 60
into a oscillatory movement of cutting section 72. Further, as
discussed below, opening 53 can be configured to direct the
movement of the proximal and distal portions when the blade is
engaged by the drive source so that that blade is a transverse
acting blade 10a. That is the cutting motion of blade at cutting
section 72 is substantially transverse to the motion of proximal
portion 60 induced by drive source 20 as is shown in FIG. 3b. Also
as discussed herein, opening 53 can also define top and bottom
portions of the blade such as top and bottom portions of the
proximal portion 60 of the blade.
One or more openings 53 can also be configured for debris
collection, aspiration or irrigation, or access of a viewing
device. In alternative embodiments, additional openings can be used
for debris collection and/or irrigation, aspiration or access of a
viewing device (e.g., a fiber optic view device) In such
embodiments, the opening can comprise a channel running along all
or a portion of the blade. Typically, such channels will run along
a longitudinal axis of the blade, but they can also be laterally or
otherwise oriented. In one embodiment one opening can be used for
aspiration, one for irrigation and another for a viewing device.
The openings can be configured to allow for continuous or near
continuous aspiration/irrigation or viewing with the viewing
device. In use, this allows the surgeon to continue with cutting
procedure without the need to stop for one or more of aspiration,
irrigation or viewing of the tissue site since he can be
continuously be performing these operations during the cutting
procedure.
A discussion will now be presented of the configuration of the
proximal and distal portions of the blade. In many embodiments, at
least a portion of blade 10 is configured to be inserted through an
incision site 30i to cut underlying target bone at target tissue
site 30. Accordingly, blade 10 including proximal portion 60 will
typically have a substantially straight shape so as to access and
cut tissue directing beneath the proximal portion. However in
alternative embodiments (not shown), the proximal portion can 60
have a curved, right angle or even a U shape so as to access tissue
that is offset from or otherwise not directly underneath the
incision site. In use, such embodiments allow the surgeon to cut
target bone or other tissue that is obstructed by other anatomical
structures such as bone, organs, vasculature and nerves. For
example, in one embodiment a blade having a right angle shaped
proximal portion could be used to cut tissue that is within a
cavity or recess of other tissue. Similarly, embodiments of the
proximal member having a curved shape can be used to maneuver
around curved tissue structures such as organs or blood vessels to
reach a target site without cutting them. Also in many embodiments,
proximal portion 60 can have a tapered section 60T. The non tapered
or wider portion of proximal portion 60 can be configured for
engagement with a reciprocating drive source while the tapered
section has a smaller width allowing easier access to a selected
tissue site.
In many embodiments, proximal portion 60 includes a longitudinal
slot 63 extending along the length of the proximal section and
defining top and bottom proximal portions 60t and 60b. Typically,
slot 63 will be positioned on a longitudinal center line 52c so as
to bisect the proximal portion into equal top and bottom portions.
Alternatively, slot 63 can be positioned off-center line 52c. Also
slot 63 will typically be continuous with an opening 73 in distal
portion 70 so as to form opening 53. In such embodiments, slot 63
can also be used for purposes of irrigation or aspiration of the
tissue site. Alternatively slot 63 can be discontinuous from
opening 73.
Engagement section 62 can comprise any portion of proximal portion
60. In many embodiments, engagement section 62 comprises an opening
64 as is shown in the embodiment of FIG. 3a. Typically, opening 64
will be continuous with slot 63 such that when drive source 20
engages opening 64 it produces longitudinal motion of top portions
60t (or bottom portion 60b) along slot 63 which is converted to
lateral motion at the distal portion of the blade 70 as is shown in
FIG. 3b. In these and related embodiments, the surface 64s of
opening 64 can be configured to function as a cam follower. The
profile 64p of surface 64s can be configured to control the amount
of longitudinal movement 60m of proximal portion 60 and thus in
turn the amounts of lateral movement of 72M of cutting section 72.
In a similar respect profile 64p can be used to control the speed
of the cutting section 72. In various embodiments, profile 64p can
be diamond shaped, circular, oval, parabolic, hyperbolic or other
curved profile. In a preferred embodiment profile 64p has as
rounded diamond shape as is shown in FIG. 3A. Also in alternative
embodiments profile 64p can be modified by means of fitting (not
shown), such as a snap in fitting, which fits into or otherwise
couples with opening 64. In use, such a fitting would allow the
surgeon to modify the displacement of blade 10, without having to
change blades.
In other embodiments, engagement section 62 can comprise all or a
portion of proximal end 61. The width 62W of the engagement section
can be larger than that of other portions of proximal portion 60 so
as to present more surface area for contact by drive source 20. For
embodiments having slot 63, engagement section will comprise a top
and bottom portion 62t and 62b. In such embodiments, top and bottom
portion 62t and 62b can be configured to be independently and
reciprocally engaged by drive source 20. That is each portion (62t
and 62b) can reciprocate proximally and distally independent of the
other portion. For example, in one embodiment during the course of
one drive cycle, the drive source exerts a force to longitudinally
displace for example, top portion 62t in a distal direction D while
exerting little or no force on bottom portion 62b. This causes top
proximal portion 60t to also be longitudinally displaced. During
the next portion of the cycle, the drive source disengages top
portion 62t (allowing it to reciprocate back to its original
position) and now forcibly engages bottom portion 62b causing it to
be displaced distally along with bottom 60b. This reciprocal motion
is subsequently converted by distal portion 70 into an oscillatory
movement of cutting section 72 as is discussed herein. These and
related embodiments allow the cutting action of the blade to be
isolated to cutting section 72 and thus eliminate or minimize
injury to tissue in contact with other portions of the blade.
A discussion will now be presented of distal portion 70. As
described above, distal portion 70 includes distal end 71 and a
cutting section 72. Typically cutting section 72 is placed at
distal end 71 but can also be placed at other location along distal
portion 70. In many embodiment, cutting section 72 comprises a
plurality of teeth 74, but can also comprise a single sharp edge 75
or a combination of edge and teeth (e.g. similar to a serrated
knife). Teeth 74 can be hardened relative to the remainder of blade
10 to improve their ability to cut bone. Also the hardness, pitch
and dimensions of teeth 74 can be selected for the particular bone
tissue to be cut. The smaller teeth and pitch can be used for finer
cuts in, for example, spinal tissue, whereas larger teeth and pitch
can be used for cuts to the distal or proximal femur or tibia. In
one embodiment, the teeth can have a finer pitch in the central
portion of the blade and a coarser pitch along the outer edges of
the blade. Also the teeth can be symmetrical, angled (e.g., by
45.degree.), right angled (e.g., by 90.degree.) as well as being
arrayed on an arc line. In various embodiments, cutting section 72
and teeth 74 can be configured to cut different types of bone
tissue including one or more of femoral, tibial, hip, spinal or
cranial or dental mandibular or other bone tissue.
In various embodiments, distal portion 70 is configured to convert
or translate longitudinal or other movement of proximal portion 60
into lateral or other movement of cutting section 72 sufficient for
the cutting of bone. In many embodiments, this can be achieved by
the use of one or more spaces 73 disposed within the body of the
distal portion. Space 73 can have a shape and size configured to
act as a pivot or motion converter 73c where it converts reciprocal
longitudinal movement of the top and bottom portions of proximal
portion 60 into lateral oscillatory movement of cutting section 72.
Thus space 73 can act as one or more of a transverse motion
converter and/or a reciprocal to oscillatory motion converter.
Typically, space 73 will have at least a partly rounded shape and
can include shapes such as circle, ellipse, oval, cassini oval or
rounded rectangle and the like but also have a rectangular or other
un-rounded shape. Space 73 can comprise a plurality of spaces 73'
having the same or different shape arranged in a pattern 73P. In
one embodiment shown in FIGS. 1a and 1b, space 73 can comprise a
single space having a rounded rectangular shape wherein the space
is continuous with slot 63. In another embodiment shown in FIGS. 2a
and 2b, the spaces can comprise a plurality of spaces having a
central space 73' surrounded by series of secondary spaces 73 which
can have an elongated oval or other shape.
In preferred embodiments, space 73 has a distally tapered and/or a
tapered oval shape configured to produce a substantially constant
stress or constant moment arm 70malong the length of distal section
70 as is shown in FIG. 3a. These and related embodiments can be
configured to produce one or more of the following: i) more control
over the amount of lateral deflection of the lateral section
include the cutting section; ii) reduced stress concentration in
the distal section of the blade; and iii) reduced risk of shear
failure of distal sections of the blade during use.
As shown in FIG. 3b, the longitudinal movement of the proximal
section 70 is converted to lateral movement of the distal section
70. In various embodiments, the blade can be configured to produce
selected amounts of lateral movement 72M of cutting section 72 with
minimal or no lateral movement of the rest of the blade such that
the cutting action of the blade is confined to cutting section 72.
Preferably, the amount of lateral movement 72M of section 72 (as
well as that of the remainder of the blade) is less than about
0.125'' so as to minimize injury or disruption to surrounding
tissue. In use, such minimal lateral movement allows blade 10 to be
used to make long lateral cuts 30c in subjacent bone or other
tissue with minimal injury to surrounding tissue as is shown in
FIGS. 4a and 4b. Further, the lateral cuts 30c can be made to very
deep subjacent tissue, for example six inches or deeper, without
the need to retract surrounding tissue or make large incisions to
get the cutting section of the blade near the target tissue site.
Also, the cuts can be made in a continuous motion without the need
to stop due to potential trauma to surrounding tissue. Such
continuous motion results in a more uniform and faster cut. These
factors allow embodiments of blade 10 to be used in a number of
minimally invasive surgical procedures.
The amount of lateral movement of cutting section 72 can be
controlled by several factors including the selection of the size
and shape of space 73 in relation to space 63. Typically, space 73
will have larger width 73W than width 63W of space 63. The ratio
between the two can be in the range of 2:1 to 10:1 or larger. In
many embodiments, space 63 comprises a narrow slot and thus space
73 will have a much larger width than space 63. The ratios between
the two widths can be used to control the ratio between the amount
of movement between the proximal portion and the cutting portion as
well as the ratio between the speeds of the two portions. Larger
ratios of width 73W to width 63W will tend to produce greater
amounts of movement of cutting section 72. In various embodiments,
the ratio between the amount of movement (and the speed) of the
proximal portion 60 and the cutting section 72 can range from 1:10,
to 1:1 to 10:1. This ratio can be selected depending upon the
surgical application. Smaller amounts of movement of the cutting
section can be selected for procedures requiring finer cuts such as
spinal and/or neurological procedures.
Typically, distal portion 70 and/or converter 73c are configured
produce movement of the cutting section 72 that is substantially
transverse (i.e. perpendicular) to direction of movement or
proximal portion 60 as is shown in FIG. 3b. However in various
embodiments, converter 73c can have a shape and size configured to
produce conversion in the direction of movement of the cutting
section at other angles to the movement of the proximal portions,
for example, 30, 45 or 60.degree.. In such embodiments, the cutting
section 72 can itself be positioned at a non-transverse angle with
respect to longitudinal axis 51. In such embodiments, converter 73c
can have one of a tear like shape which can be at selected angle to
longitudinal axis 51.
Blade 10 can have a shape 10s and length 10L configured for a
number of surgical procedures including various orthopedic,
neurological or other procedures. In various embodiments, the
length 10L of the blade can be in the range of 0.5 to 10 inches,
with specific embodiments of 1, 2, 3, 5 and 8 inches. The length,
chemical composition, mechanical properties, and shape of the blade
as well as those of the proximal and distal portions can be adapted
for particular surgical procedures. As discussed above, in various
embodiments, the blade can have a curve, right angle or U-shape to
access various tissue sites that are recessed or directly
obstructed by other tissue which can not be readily retracted.
Also, the blade length as well as shape can be adapted for use in
various minimally invasive and arthroscopic procedures.
Accordingly, the blade can be adapted to fit through various
surgical ports and conduits used in minimally invasive procedures.
Particular embodiments of the blade can also be adapted to produce
a very fine cutting motion of cutting section 72 with minimal
and/or reduced vibration or movement of non cutting portions of the
blade including proximal portion 60 and portions of distal portion
70. Such applications can include various neurological, spinal and
other procedures where fine cutting action and minimal vibration is
desirable so as to not exert a level of injurious force on
surrounding non-target tissue. In use, such embodiments permit a
surgeon to access and cut bone or other tissue that is adjacent to
very delicate tissue such as nerves and vasculature including
microvasculature without trauma or injury to the adjacent tissue.
For example an embodiment of a transverse action low vibration
blade can be used to perform various minimally invasive spinal
procedures, e.g., removal of tissue or calcification such as during
a laminectomy, where there is closely adjacent nerve, vascular or
other sensitive tissue. In related embodiments, the cutting section
of the blade can be positioned on or in an internal structure or
organ such as the brain, kidney, heart or liver and a cut made with
the cutting section where vibration of the remainder of the blade
does not cause hemorrhage of a vascular structure of the structure
or organ including a vasculature structure on the surface of the
organ such as the vascular network on the surface of the brain. In
various embodiments the size, shape and mechanical properties of
the blade can be adapted for particular tissues sites (e.g., the
brain, spine, etc) so as to allow cutting of tissue at the site
while minimizing or preventing hemorrhage and other tissue trauma
as described herein. This can be accomplished for example, by
matching the amount of vibration and other movement of the non
cutting portions of the blade to the particular tissue site.
In various embodiments, blade 10 can be fabricated from a number of
or matrix of surgical grade metals, ceramics or composites known in
the art. Preferably cutting section 72 including teeth 74 comprise
surgical grade stainless steel material, for example, hardened and
tempered stainless steel. However, these materials may be alloyed
or substituted with other material, such as cera-metallic
composites. When blade 10 comprises a metal, all or a portion of
the blade can be fabricated using forging, machining or other metal
fabrication methods known in the art. Also, the blade can be
treated or processed using one or more metal treatment methods
known in the art as is described herein.
Material for blade 10 can be selected based on one or more
properties including elastic modulus, elastic limit, tensile
strength, yield strength, compressive strength, resonance
frequencies, and hardness. Selection of a resonant frequency(s)
allows the blade to have sufficient lateral motion of the cutting
section for cutting for a given input frequency by the drive
source. It also allows the blade to be self governing such that
when a threshold amount of force is applied to the blade by the
surgeon, the blade becomes over-damped and cutting action of the
blade is ceased.
In various embodiments, the saw blade material may be a composite.
Composite include a combination of at least two materials in which
one of the materials, called the reinforcing phase, is in the form
of fibers, sheets, or particles, and is embedded in the other
material called the matrix phase. The reinforcing material and the
matrix material can be metal, ceramic, carbon-fiber, polymer, or
any combination thereof to produce a saw blade that converts
atraumatic, longitudinal motion along the sides of the saw blade to
transverse motion of the toothed end of saw blade, allowing
effective cutting and or resection of selected tissue or bone. In
embodiments where the blade comprises a composite, the composite
can be configured to confer to different properties (e.g.
stiffness, strength, hardness, etc) to different portions of the
blade. For example, the proximal portion can be configured to have
greater lateral stiffness, and conversely, the distal portion more
laterally flexible. Also, the cutting section and/or the engagement
section can be configured to be harder and/or tougher.
Also in various embodiments, different portions of the blade may
have different properties. For example cutting section 72 including
teeth 74 can be fabricated from harder materials then other portion
of distal portion 70 or proximal portion 60. In other embodiments
different portions of the blade can have different stiffnesses.
Further the difference in stiffness can be in different directions.
For example, proximal portion 60 can be have a higher lateral
stiffness than distal portion 70, but a lower longitudinal
stiffness. Such embodiments can be configured to bias or otherwise
facilitate the proximal portion to bend and flex longitudinally
with minimal lateral deformation, and the distal portion to bend
and flex laterally with minimal longitudinal deformation. As is
discussed herein, this allows blade 10 to be used such that cutting
section 72 can move laterally to cut bone tissue without trauma to
tissue caused by lateral movement of proximal portion 60.
In various embodiments, one or more sections of the blade can be
treated using one or more metallurgical treatments known in the
art. Such treatments can include without limitation, annealing,
tempering, stress relieving and work hardening. Further these and
other treatments can be utilized to fabricate embodiments of the
blade having portions with differences in material properties as
described above. For example in one embodiment, a section 76 of
distal portion 70 can be annealed or tempered to increase
elasticity/flexibility and reduce brittleness. This increased
elasticity can serve to have selected sections of distal portion 70
have an increased flexibility in relation to proximal portion so as
to enhance the lateral movement and cutting action of cutting
section 72 in response to the application of force from drive
source 20 while minimizing the lateral movement of proximal portion
60. In various embodiments, tempering and annealing can be achieved
using laser methods wherein the desired section is annealed or
tempered by a laser beam to achieve the desired property with
minimal effect to surrounding portions of the blade. Such methods
allow for the precise placement of blade sections having desired
material properties so as to control the amount and direction of
deformation of sections of the blade in response to the application
of force, for example from drive source 20. In other embodiments,
laser annealing or other annealing or tempering methods can be used
to produce a linear or gradual transition in material properties
between sections of the blade vs. a stepped transition.
In many embodiments, blade 10 is incorporated into a saw device 25.
The device can have a variety of shapes and sizes known in the
surgical arts and be configured to be held in one or both hands and
can also be configured to be used with a cutting guide described
herein. Also blade 10 can be adapted to fit on various conventional
surgical saws known in the art. Also embodiments of the invention
can include a kit for doing so (e.g. an adaptor or fitting).
A discussion will now be presented of drive source 20. In various
embodiments, drive source 20 can be electromechanical, pneumatic or
hydraulic based. Example electro-mechanical drive sources include
electric motors (AC and DC), piezo-electric systems and the like.
Example electric motors include rotary DC brushless motors.
Preferably, drive source 20 is configured to engage the engagement
section 62 of blade 10 so as to cause reciprocating longitudinal
motion of the proximal portion 60. The drive source can also be
configured to induce motion of proximal portion 60 in other
directions and manners.
In one embodiment shown in FIGS. 5a-5d, drive source 20 can
comprise a rotary mechanism 20r comprising two or more drive
members 21 which rotate approximately 180.degree. of phase and
press against opposite halves of surfaces 64s so as to produce
reciprocal longitudinal movement of the top and bottom proximal
portions 60t and 60b of blade 10. FIGS. 5b-5c show how when drive
members 21 rotate against the surface 64s of opening 64 they
produce reciprocal longitudinal movement of proximal portions 60t
and 60b so as to cause lateral oscillatory movement of cutting
section 72. FIG. 5b shows the blade and cutting section in a
neutral position 72n; 5c shows the cutting section 72 laterally
displaced to a top position 72t; and 5d shows the cutting section
laterally displaced to a bottom position 72b. In use, drive members
21 function as cams 21c, portions 60t and 60b as cam followers 60f
and surface 34s as a cam follower surface. Mechanism 20r can be
pneumatically powered, but is preferably electrically powered, for
example, by a DC or AC motor.
Mechanism 20r can also include one or more guides, restraining
members or dampeners 22 shown in FIG. 5a, which constrain movement
of proximal portions of the blade to a purely longitudinal
direction. For ease of discussion, members 22 will now be referred
to as dampeners 22, but other forms are equally applicable. In one
embodiment dampeners 22 can be a metal or plastic bands or
cylinders. Dampeners 22 can constrain movement of the blade to a
longitudinal direction for sections of the blade that are bounded
by the guides. They can also substantially constrain movement of
the blade to a single plane. Dampeners 22 can be positioned at any
point along blade 10 but are preferably positioned on proximal
portion 60. Also the positioning of the bands can also be used to
control both the longitudinal and lateral movement of the blade.
For example, greater amounts of lateral movement can be obtained by
positioning the bands more proximally along the blade. In various
embodiments, blade 10 can include any number of dampeners 22 but
preferably, includes at least two pairs of dampeners and more
preferably includes three pairs of dampeners.
In the embodiment shown in FIG. 5a, mechanism 20r can be configured
to be mounted in a handheld device 20h which can comprise saw
device 25. For ease of discussion handheld device 20h will now be
referred to as saw device 25. For embodiments where saw device 25
is electrically powered the device can be configured to use
external electrical power (AC or DC) or can be battery powered
using a battery pack (e.g. lithium, nickel metal hydride, etc). Saw
device 25 can include one or more connections or conduits 25C for
electrical, pneumatic, or hydraulic connections both for powering
drive source 20, and for light transmission, aspiration/vacuum, or
the like. Connections 25C can also be configured for connection to
processors internal to the device and sensors positioned on the
blade 10 or elsewhere. Device 25 can also include control knobs or
trigger mechanisms coupled to rheostats or other electronic
device(s) or control device for controlling the speed of blade 10.
The saw device 25 can also include a display (not shown) for
displaying various cutting parameters such as blade speed, blade
travel, applied force, and the like.
In various embodiments, device 25 and/or blade 10 separately can be
configured for coupling to computer controlled robotic surgical
systems. Accordingly in such embodiments connections 25C can be
configured to be coupled to one or more inputs to the robotic
surgical a systems to provide for connections to sensors, power
systems or processors coupled to device 25 and/or blade 10. Also,
the shape of device 25 and/or blade 10 can configured to be grasp
or otherwise be engaged by a robotic arm or device of the robotic
surgical system. Example robotic surgical systems include the da
Vinci.RTM. Surgical System manufactured by Intuitive Surgical
(Sunnyvale, Calif.)
In other embodiments blade 10 can be configured to be engaged by a
reciprocating drive source including an asynchronous reciprocating
drive source. For example, in an embodiment shown in FIGS. 6a and
6b, the drive source can comprise two reciprocating members 21r
such as cams or pistons which are configured to engage the top and
bottom portions 61t and 61b of proximal end 61 that collectively
comprises engagement section 62. Preferably in this and related
embodiments, the reciprocating members are approximately
180.degree. out of phase such that when one member is pushing
against for example the top engagement portion 62t the other member
is exerting little or no force on the bottom portion 62b. Other
amounts phase angles are also contemplated. Also the drive source
20 and blade 10 can be configured to drive cutting section 72
through speeds (e.g. oscillations rates) which can range from about
50 to 1000 oscillations per second or greater.
In alternative embodiments, the drive source can comprise a voltage
source and all or a portion of proximal portion 60 is fabricated
from a piezo-electric material configured such that when it is
energized by the voltage source it flexes or contracts causing
reciprocal movement of the proximal portion which in turn is
converted into lateral motion of the cutting section. In one such
embodiment, the drive source can be an AC voltage source where the
top and bottom portions of proximal portion 60 are configured to
reciprocate back and forth in a longitudinal direction from the AC
voltage. In such embodiment the speed of the reciprocation and thus
the oscillation of cutting section 72 can be controlled via the
frequency of the AC current.
Referring now to FIGS. 7a and 7b, in various embodiments, system 5
can include a sleeve 90 configured to fit over all or a portion of
blade 10. Sleeve 90 can be configured to provide lateral support to
blade 10 during cutting such that the blade does not bow or
otherwise deform laterally during a cutting procedure or other use.
Accordingly sleeve 90 has sufficient stiffness, (e.g. bending
stiffness) to overcome any lateral or other force exerted by the
blade on the sleeve so as to prevent or minimize any lateral
deformation of the blade during use. In this and related
embodiments sleeve 90 functions as a support sleeve 91. Bending
stiffness can be achieved by selection of a combination of the
thickness and bending modulus of the material used for the sleeve.
In various embodiments all or a portion of the sleeve can be
tapered so as to have a varying stiffness along a length 901 of the
sleeve. Specific portions of the sleeve can thus be configured to
be stiffer so as to provide greater support to selected portions of
blade 10, for example those section exposed to greater amounts of
stress. In this way, the sleeve can further enhance the efficiency
in the conversion of motion from the proximal portion 60 to distal
portion 70 to enhance the cutting action of the blade at cutting
section 72 while minimizing lateral and other motion (e.g.
vibrations, etc) of the proximal portion which may cause tissue
cutting or other trauma. In specific embodiments, the sleeve 90 can
be configured to have a selected stiffness profile 90p which can be
correlated to the stress profile 10p, dimensional or other property
of blade 10.
In various embodiments, the sleeve 90 can be disposed over any
selected portion or length of the blade 10. In preferred
embodiments, the sleeve will cover most of proximal portion 60 and
a portion of distal portion 70 while leaving cutting section 72
exposed. Desirably the sleeve covers portions of the blade so as to
minimize lateral movement of proximal portion 60 but allow
sufficient lateral and/or other movement of distal portion 70 for
cutting section 72 to effectively cut selected bone or other tissue
30. Also in various embodiments, the sleeve lumen 92 can have
clearance to allow the blade to move through the sleeve. Desirably
the amount of clearance is small, for example less than about
0.005''. However, the clearance can be sufficient to allow the
sleeve lumen to act as channel 92c for the delivery of irrigation
fluid, a viewing device (e.g. a fiber optic viewing device). Also
the inner lumen of the sleeve can have a lubricous coating 92 so as
to minimize the amount of clearance and/or friction between the
blade and the sleeve. Alternatively, the sleeve can be fixedly
attached to at least a portion of the blade so as to move with the
blade.
In various embodiments, sleeve 90 can be fabricated from various
high strength plastics known in the art including for example,
polycarbonate, polyetherimide, PEEK, acrylics and one or more
thermoset plastics known in the art. Due to the stationary nature
of the sleeve 90, the sleeve can have a thickness configured to fit
tightly in slotted cutting guides known in the art, (e.g., cutting
guides used in knee replacement surgery) without causing
degradation of the dimensional integrity of the cutting guide. This
allows use of cutting guides fabricated from non hardened materials
such as injection molded plastic.
Sleeve 90 can be formed separately or can be formed over blade 10
using, for example, molding or extrusion methods known in the art.
In one embodiment the sleeve can be coated onto the blade and then
cured in place over the blade. The material for the sleeve can also
be selected from materials that are compatible with one or more of
EthO, gamma or e-beam or other sterilization methods known in the
art. Also, the sleeve can be configured (e.g., through the
selection of the material and dimensions) to allow the blade to be
sterilized when the sleeve is mounted over the blade. This can be
achieved through the selection of the material and dimensions of
the sleeve
Referring now to FIGS. 8-9, in various embodiments, blade 10 can
also be configured to have various mechanical properties to allow
the blade to perform one or more functions which supplement its
cutting function. For example, in some embodiments, the blade can
be configured to control the amount of force that the physician can
apply to the blade and still have the blade cut. This can be
accomplished by configuring the stiffness (e.g. column stiffness)
or other mechanical properties of the blade such that when a
compressive force F applied to the proximal portion 60 of the blade
exceeds a threshold, the proximal portion 60 deforms (e.g., in a
section 60d) so as to not transmit sufficient longitudinal force to
the distal portion 70 including cutting section 72 to have the
cutting section cut. In other words, the longitudinal force from
the proximal section is diverted into bending the proximal portion
of the blade instead of being transmitted and converted into
lateral movement by the distal portion. In various embodiments, the
blade can be coupled to a strain gauge (not shown) or other force
monitoring device in turn coupled to a monitor/display device to
let the surgeon know how much force he is applying.
In use, embodiments of the blade having a force regulating
capability allow blade 10 to function as a force regulating device
10F to prevent the user from applying excessive force to the tissue
site during cutting, or from progressing a cut beyond the point
that force is felt by the force regulator, thus avoiding damage or
trauma to tissue structures beyond the desired cutting area.
In other embodiments, blade 10 can be configured to provide the
surgeon tactile or other feedback as to the amount of force applied
to the blade. For example, the blade can be configured to
vibrate/oscillate at the proximal end 61 in response to the amount
of force applied and the cutting action of the blade. The
vibrations at the proximal end are then transmitted to the handle
25h or other portion of saw device 25. In specific embodiments the
amplitude and/or frequency of vibration can be lineally or
otherwise correlated to the amount of applied force. In various
embodiments, this can be accomplished by configuring the shape and
stiffness profile 11 of the blade to transmit vibrations when a
threshold amount of force is applied with increasing amounts of
force resulting in an increase in the amplitude and/or frequency of
the vibrations. Alternatively, the blade can be configured such
that increasing amounts of force results in a decrease in the
amplitude and frequency of vibrations. In one embodiment, the blade
can be configured to start and then stop vibrating/oscillating over
a selected range of applied pressure so as to provide the surgeon
with tactile or other feedback on when he is in or out of the
operational window of the proper amount of applied force. In
related embodiments, a sensor 12 such as a MEMS accelerometer, MEMS
pressure sensor, piezo-electric sensor or a microphone, can be
coupled to the blade and in turn to a monitoring means to provide
the surgeon with a quantitative indication of the amount of
vibrations/oscillation/speed and in turn the amount of applied
force. In various embodiments, sensors 12 can be coupled to a
processor 13 including a display 13D so as to display a sensor
output 120, for example applied force in graphical, numerical or
other format. The blade 10 including the sensors 12 can be coupled
to the display through a connection 25w or they can be configured
to send a wireless signal 12s. In one embodiment, an audio output
can be generated from the sensor to provide the surgeon an audio
signal indicative of the applied pressure. In these and related
embodiments, blade 10 acts as a transducer 10T, to provide the
physician a qualitative and/or quantitative indication of the
amount of force he is applying to the blade and thus to the cutting
site 30. In use, such embodiments allow the surgeon to readily stay
within the optimal range or window of applied force to the cutting
site without the need to look away from the surgical field and/or
interrupt the cutting procedure. This provides for one or more of
the following: i) safer cuts because of more precise control of the
applied force during the cutting process thus avoiding potential
damage to adjacent tissue; ii) more precise and accurate cuts as a
result of maintaining force feedback/regulation allowing the
surgeon to maintain the saw blade in its most effective cutting
mode. Further embodiments using force transducing blades 10T allow
the surgeon to know when the blade has or is about to enter into
softer tissue (e.g. cartilage, etc) because the amount of force on
the blade will drop off due to the decrease in the opposing force
from the progressive thinner section of uncut bone.
Referring now to FIG. 10, in various embodiments, system 5 can
include a cutting guide 100 configured to be used with embodiments
of blade 10 in making cuts in bone or other tissue. Cutting guide
100 is configured to guide blade 10 in making various angled,
chamfered or other shaped cuts 30s. Further description of cutting
guides is found in U.S. patent application Ser. No: 11/149,944
which is fully incorporated by reference herein.
Alternative Embodiments
A number of alterations of the blade 10 can be made to accommodate
different drive sources, access different surgical sites, (e.g. the
brain, spine, etc) achieve different amounts of lateral
displacement of the cutting section and/or produce different blade
speeds and cutting forces. These alterations can be adapted to the
particular surgical application, e.g. the femur where higher amount
of cutting force may desirable, vs. the brain where lower forces,
lower blade speeds may be more desirable. For example the proximal
portion of the blade can elongated so as to produce smaller lateral
displacement of the cutting section but with higher amounts of
cutting force (analogous to gear torque).
FIGS. 11-14 illustrate several alternative embodiments of blade 10
incorporating one or more of these or other alterations. FIG. 11
shows an embodiment of the blade having an integral guards or stops
15 which limits the amount of lateral movement 10lm of portions of
blade 10. FIG. 5a also shows an embodiment of the blade having a
stop 15. Stops 15 can extend over all or a portion of the length of
blade 10. Typically, blade 10 will include a pair 15p of stops 10g
so as to limit lateral movement of the blade on both sides.
Alternatively, the blade can include only one stop 15 so as to
limit motion on only one side of the blade. Embodiments of the
blade having stops 15 can also be configured to be used with a
sleeve 90 as is shown in FIG. 11. Sleeve 90 can serve to limit or
dampen any vibrations that stop 15 does not. This combination
provides an additional or otherwise enhanced means for limiting
lateral movement and vibrations of portions of blade 10 so as to
reduce the transmission of movement of vibration to surrounding
tissue. In use, such embodiments serve to stabilize the blade 10
allowing the surgeon finer control over motion of the blade in
various surgical procedures.
FIG. 12 shows an embodiment of blade 10 having inwardly convoluted
portions 70c. Convoluted portion 70c serves to convert longitudinal
movement of the proximal portion 60 to lateral movement of cutting
section 72. The convoluted portions 70c also serve as a motion
director 70md to control or limit any lateral movement of the
distal portion 70 to an inward direction with respect longitudinal
axis 51. FIG. 13 shows another embodiment of a blade having
convoluted portions 70c. In this embodiment the blade is configured
to be engaged by a piston or piston like drive source 20.
FIG. 14 shows an embodiment of blade 10 having an outwardly tapered
t space 73ot or motion converter 73c which extends in a longer
direction proximally than other embodiments. The increased length
and outward taper of space 73ot can be configured to produce
increased amounts of lateral motion 72m of section 72. Also space
73ot can be configured to decrease the amount of force the cutting
section applies to tissue. Such embodiments can be used for tissue
sites having softer tissue, e.g., muscle tendons fascia, etc.
Conclusion
The foregoing description of various embodiments of the invention
has been presented for purposes of illustration and description. It
is not intended to limit the invention to the precise forms
disclosed. Many modifications, variations and refinements will be
apparent to practitioners skilled in the art. Also, the teachings
of the invention have broad application in the field of surgical
saws and instruments including instruments used in minimally
invasive orthopedic procedures. They also have application to field
of cranio-facial instruments and related procedures as well to the
field of neurosurgical instruments and related procedures.
Further, elements or acts from one embodiment can be readily
recombined or substituted with one or more elements or acts from
other embodiments to form new embodiments. Moreover, elements that
are shown or described as being combined with other elements, can
in various embodiments, exists as stand alone elements. Hence, the
scope of the present invention is not limited to the specifics of
the exemplary embodiments, but is instead limited solely by the
appended claims.
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